Identification of molecular markers associated with leptine production in a population of Solanum chacoense Bitter

Solanum chacoense Bitter, a wild relative of the cultivated potato, produce s several glycoalkaloids, including solanine, chaconine, and the leptines. The foliar-specific leptine glycoalkaloids are believed to confer resistanc e to the Colorado Potato Beetle (CPB). Using two bulked DNA samples compose d of high and low-percent leptine individuals from a segregating F-1 popula tion of S. chacoense, we have identified two molecular markers that are clo sely linked to high percent solanine + chaconine and, conversely, to nil/lo w percent leptine. One of these, a 1,500-bp RAPD product (UBC370-1500), had a recombination value of 3% in the F-1 progeny, indicating tight linkage. UBC370-1500 mapped to the end of the short arm of potato chromosome 1, in t he region of a previously mapped major QTL for solanidine, from a S. tubero sum (solanidine)x S. berthaultii (solasodine) cross. Taken together, these results suggest that either (1) a major locus determining solanidine accumu lation in Solanum spp. is on chromosome 1 in the region defined by the RFLP markers TG24, CT197, and CT233, or (2) this region of chromosome 1 may har bor two or more important genes which determine accumulation of steroidal a glycones. These findings are important for the genetics of leptine las well as other glycoalkaloid) accumulation and for the development of CPB-resist ant potato varieties.